1. Field of the Invention
This invention is related to a method for improving genotypes and associated phenotypes in Brassica species by means of Agrobacterium-based genetic transformation.
2. Background
Cruciferous species of the tribe Brassiceae are widely used as a source of protein, oil, condiments and chemical feedstocks. Significant effort has been expended to improve the quality of cultivated Brassica species by conventional plant breeding, and a number of major successes are recorded. The methods of conventional plant breeding have been limited, however, to the movement of genes and traits from members of the genus Brassica to other of the same genus and, in a few notable examples, "wide crosses" from other closely related genera. The development of a method for introducing foreign genes into Brassica species would greatly enhance the range of traits which could be imparted to Brassica oilseeds and vegetables.
In order to obtain a reliable system for useful gene introduction into Brassica species, a number of obstacles must be overcome. These include optimization of regenerability to whole plants of the target tissue, definition of the conditions (e.g., time, bacterial concentration, and media) for the co-cultivation of the Brassica cells and Agrobacterium cells, discovery of an Agrobacterium strain of suitable virulence with Brassica for gene transfer, identification of a suitable regulatory sequence (promoter) to ensure expression of the foreign gene in the transformed tissue, and expression of a selectable marker enabling identification of transformants.